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As an important soil and water conversation endeavor, the 'Grain for Green' project launched by the Chinese Central Government almost doubled the vegetation cover on the Loess Plateau between 1999 and 2013. The corresponding vegetation restoration considerably diminished slope erosion throughout the Loess Plateau, although erosion in gullies remains poorly understood. In this paper, a composite fingerprinting approach was employed to assess the relative importance of the erosion of gully and slope soils within a typical dam-controlled catchment of the Loess Plateau. A total of 23 couplets were identified based on the deposited layer thicknesses and extreme rainfall event records along the sediment profile. The results suggest that gullies contributed 71% to the overall sediment proportion, and those sediments had an increased tendency to accumulate during 2010-2016 under the 'Grain for Green' project. The sediment inputs from slope areas were predicted to be 29%. The eroded gullies materials mainly consisted of silt-sized particles, which dominated the eroded sediment. Silt particles with sizes of 0.02-0.05 mm constituted the main particles in both deposit sediments and gully materials, whereas the slope areas mainly contained particle sizes of <0.01 mm. The check dam proved to be effective at trapping coarse silt with 27-42% of the total sediment content. This study presents reliable information on the importance of gullies as sediment source materials and verifies the applicability of tracing procedures for collecting information on sediment effluxes from both slopes and gullies.

Understanding the soil and water conservation (SWC) impact of steep-slope agricultural practices (e.g. terraces) has arguably never been more relevant than today, in the face of widespread intensifying rainfall conditions. In Italy, a diverse mosaic of terraced and non-terraced cultivation systems have historically developed from local traditions and more recently from the introduction of machinery. Previous studies suggested that each type of vineyard configuration is characterised by a specific set of soil degradation patterns. However, an extensive analysis of SWC impacts by different vineyard configurations is missing, while this is crucial for providing robust guidelines for future-proof viticulture. Here, we provide a unique extensive comparison of SWC in 50 vineyards, consisting of 10 sites of 5 distinct practices: slope-wise cultivation (SC), contour cultivation (CC), contour terracing (CT), broad-base terracing (BT) and oblique terracing (OT). A big-data analysis approach of physical erosion modelling based on high-resolution LiDAR data is performed, while four predefined SWC indicators are systematically analysed and statistically quantified. Regular contour terracing (CT) ranked best across all indicators, reflecting a good combination of flow interception and homogeneous distribution of runoff and sediment under intense rainfall conditions. The least SWC-effective practices (SC, CC, and OT) were related to vineyards optimised for trafficability by access roads or uninterrupted inter-row paths, which created high upstream-downstream connectivity and are thus prone to flow accumulation. The novel large-scale approach of this study offers a robust comparison of SWC impacts under intense rainstorms, which is becoming increasingly relevant for the sustainable future management of such landscapes.

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